Magnetic Nanostructures with Perpendicular Anisotropy for Room Temperature Skyrmions

摘要：磁skyrmions是一种特殊的磁矩排列，遵循特定的绕组结构。它们具有一些迷人的特性。例如，它们不能连续变形到所有矩都指向同一方向的状态。Skyrmion的磁性结构一旦形成是稳定的，但一个关键的挑战是在环境条件下实现磁性Skyrmion。这个项目的重点是建造在高温下运行的人造天空粒子阵列。使用一套实验技术和模拟技术研究了这些天空的物理性质。这些人造粒子有望在室温和零磁场条件下保持稳定，从而为探索有趣的粒子物理学提供了一个令人兴奋的新平台。它们也可能在高能效数据存储、磁存储器和逻辑器件中有潜在的应用。该项目提供了在大学以及国家实验室和用户设施中培训初级研究人员的机会。首席研究员计划发起并积极参与各种努力，通过提供课程、实习、与合作大学的互访以及磁学会议上的其他具体项目，扩大代表性不足群体的参与。技术摘要：在宏观区域上实现了基于垂直各向异性纳米结构的室温人工晶格。采用多步纳米加工工艺，实现了多种人工磁性栅格，包括嵌入式栅格、栅格“赛道”和曲面基板上的栅格。根据一组磁场序列建立了粒子状态。通过微观结构表征、磁强计、一阶反转曲线、磁成像、极化中子反射和磁输运测量，探讨了天际线的空间和磁分布、拓扑特征、稳定性、迁移率和对外部刺激的动态响应。模拟是用来提供洞察力和指导实验。这些研究不仅有助于推进对人工磁性skyrmions的基本理解，而且由于skyrmions的拓扑保护量子态，在低耗散信息存储，磁存储和逻辑器件方面具有潜在的重要技术影响。它们还提供了在“超越摩尔定律”时代改变未来纳米电子学能源格局的潜力，这与国家战略计算计划和大数据计划是一致的，也是未来纳米电子学的重大挑战。首席研究员计划发起并积极参与各种各样的努力，通过他对磁学社区的广泛服务，扩大国际社会，学生，女科学家和其他代表性不足的群体的参与。参与该项目的学生将获得在大学、国家实验室和其他研究机构进行研究的良好机会。

Non-Technical Abstract:Magnetic skyrmions are a special type of arrangements of magnetic moments following a particular winding configuration. They possess some fascinating properties. For example, they cannot be continuously deformed to a state where all the moments point to the same direction. Skyrmion magnetic configurations are stable once they are formed, but a key challenge has been the realization of magnetic skyrmions at ambient conditions. This project focuses on construction of artificial skyrmion arrays, operational at elevated temperatures. The physical properties of these skyrmions are studied using a set of experimental techniques as well as simulations. These artificial skyrmions are expected to be stable even at room temperature and in zero magnetic field, thus are an exciting novel platform to explore the intriguing skyrmion physics. They also may have potential applications in highly energy-efficient data storage, magnetic memory and logic devices. This project provides opportunities to train junior researchers in university as well as national laboratory and user facilities. The principal investigator plans to initiate and actively participate in a variety of efforts to broaden participation from underrepresented groups through course offering, internships, exchange visits with partner universities, and other specific programs at the Magnetism Conference.Technical Abstract:Room temperature artificial skyrmion lattices based on nanostructures with perpendicular anisotropy are realized over macroscopic areas. A multi-step nanofabrication process is employed to achieve a variety of artificial magnetic skyrmions, including embedded skyrmion lattices, skyrmion "race-tracks", and skyrmion lattices on curved substrates. A set of magnetic field sequences is followed to establish the skyrmion states. Microstructural characterizations, magnetometry, first-order reversal curve, magnetic imaging, polarized neutron reflectometry, and magneto-transport measurements are carried out to probe the spatial and magnetic profile of skyrmions, their topological characteristics, stability, mobility, and dynamic responses to external stimuli. Simulations are employed to provide insight and guidance to the experiments. These studies not only help to advance fundamental understanding of artificial magnetic skyrmions, but also have potentially important technological impacts in low dissipation information storage, magnetic memory and logic devices, due to the topologically protected quantum states of the skyrmions. They also offer potentials to transform the energy landscape for future nanoelectronics in the "beyond Moore's law" era, which is well aligned with the National Strategic Computing Initiative and the Big Data Initiative, as well as grand challenges for future nanoelectronics. The principal investigator plans to initiate and actively participate in a wide variety of efforts to broaden participation from the international community, students, female scientists and other underrepresented groups, through his extensive service to the magnetism community. Students involved in the project receive excellent exposure to research experience in university, national laboratory and other research facilities.